Single head laser oscillator-amplifier

Abstract

A circulating laser beam is generated in an oscillator having a gain medium. The laser beam is dumped from the oscillator to produce a laser beam pulse. The laser beam pulse is expanded and returned through the same gain medium for amplification thereof. The circulating laser beam and returning laser beam pulse travel in different paths through gain medium allowing the use of a small Pockels cell in the oscillator.

What is claimed is: 
     
       1. A method of producing a laser beam pulse comprising: generating a circulating laser beam in an oscillator having a gain medium;   dumping said laser beam from said oscillator to produce said laser beam pulse; and   returning said laser beam pulse through said gain medium for amplification thereof.   
     
     
       2. A method according to claim 1 further comprising returning said laser beam pulse in a different path through said gain medium than said circulating beam. 
     
     
       3. A method according to claim 2 further comprising amplifying said laser beam pulsein said gain medium in multiple passes therethrough. 
     
     
       4. A method according to claim 3 further comprising geometrically separating said multiple passes through said gain medium. 
     
     
       5. A method according to claim 3 further comprising polarizing said laser beam pulse for separating said multiple passes through said gain medium. 
     
     
       6. A method according to claim 3 further comprising preserving polarization of said laser beam pulsein said gain medium. 
     
     
       7. A method according to claim 3 further comprising: geometrically separating said multiple passes through said gain medium; and   polarizing said laser beam pulse for doubling said multiple passes.   
     
     
       8. A method according to claim 3 further comprising upcollimating said laser beam pulse prior to return to said gain medium. 
     
     
       9. A method according to claim 8 further comprising confining said circulating laser beam in size smaller than said upcollimated laser beam pulse. 
     
     
       10. A method according to claim 9 further comprising redirecting said amplified laser beam pulse from said gain medium against a workpiece for laser shock peening thereof. 
     
     
       11. An apparatus for producing a laser beam pulse comprising: means including an oscillator having a gain medium for generating a circulating laser beam;   means for dumping said laser beam from said oscillator to produce said laser beam pulse; and   means for returning said laser beam pulse through said gain medium for amplification thereof.   
     
     
       12. An apparatus according to claim 11 wherein said returning means are effective for returning said laser beam pulse in a different path through said gain medium than said circulating laser beam. 
     
     
       13. An apparatus according to claim 12 wherein said returning means are effective for redirecting said laser beam pulse in multiple passes through said gain medium for amplification therein. 
     
     
       14. An apparatus according to claim 13 wherein said returning means are effective for geometrically separating said multiple passes through said gain medium. 
     
     
       15. An apparatus according to claim 14 further comprising means for upcollimating said laser beam pulse prior to return to said gain medium. 
     
     
       16. An apparatus according to claim 15 wherein said dumping means comprise a Pockels cell and a polarizer optically aligned in series with said gain medium, with said Pockels cell being operable in a regeneration mode for circulating said laser beam in said oscillator, and in a dumping mode for dumping said laser beam at said polarizer to said upcollimating means. 
     
     
       17. An apparatus according to claim 16 wherein said Pockels cell is sized to channel therethrough solely said circulating laser beam in a size smaller than said upcollimated laser beam pulse. 
     
     
       18. An apparatus according to claim 16 wherein said returning means comprise a plurality of optical elements optically aligned with said medium in a different path than said Pockels cell. 
     
     
       19. An apparatus according to claim 16 wherein said optical elements comprise mirrors. 
     
     
       20. An apparatus according to claim 16 wherein said upcollimating means comprise a telescope.